core: kemi - added missing is_MESSAGE()

- GH #2331

(cherry picked from commit 8db5a12f7fab1a1fc7d50c87bbf1aee325b067c2)
(cherry picked from commit b50e0041c0d485d82434381f66c1f6d21a2d003a)

src/core/kemi.c

@@ -1019,6 +1019,16 @@ static int sr_kemi_core_is_method_prack(sip_msg_t *msg)
 	return sr_kemi_core_is_method_type(msg, METHOD_PRACK);
 }
 
+
+/**
+ *
+ */
+static int sr_kemi_core_is_method_message(sip_msg_t *msg)
+{
+	return sr_kemi_core_is_method_type(msg, METHOD_MESSAGE);
+}
+
+
 /**
  *
  */
@@ -1631,6 +1641,11 @@ static sr_kemi_t _sr_kemi_core[] = {
 		{ SR_KEMIP_NONE, SR_KEMIP_NONE, SR_KEMIP_NONE,
 			SR_KEMIP_NONE, SR_KEMIP_NONE, SR_KEMIP_NONE }
 	},
+	{ str_init(""), str_init("is_MESSAGE"),
+		SR_KEMIP_BOOL, sr_kemi_core_is_method_message,
+		{ SR_KEMIP_NONE, SR_KEMIP_NONE, SR_KEMIP_NONE,
+			SR_KEMIP_NONE, SR_KEMIP_NONE, SR_KEMIP_NONE }
+	},
 	{ str_init(""), str_init("is_UDP"),
 		SR_KEMIP_BOOL, sr_kemi_core_is_proto_udp,
 		{ SR_KEMIP_NONE, SR_KEMIP_NONE, SR_KEMIP_NONE,